The objective of this work are threefold: 1) To establish the structure of the active site components of E. coli glutamine synthetase using nmr and epr techniques. By using nuclear (1H, 13C, 31P, 15N) spin lattice relaxation times obtained by fourier transformed nmr techniques, distances between paramagnetic probes and substrate nuclei will be obtained. 2) To establish the structural relationships among the metal ion site(s), catalytic site and allosteric effector sites of E. coli glutamine synthetase. Since the effector molecules have a profound effect on the catalytic activity of glutamine synthetase, the mapping experiments proposed herein will be the first indication in solution, of how structural relationships between an active site and effector site on a protein surface serve to modulate enzyme activity. 3) To determine if various probes, e.g., Cr(III)ATP and Co(III)ATP, can be utilized as substitutes for substrates and metal ions in the glutamine synthetase reactions. This class of probes can also be utilized for distance measurements utilizing nmr and epr experiments.